祁连山地区过去500 a年代际旱涝事件演化及驱动因素分析OA北大核心CSTPCD

Qilian Mountains is a climate-sensitive area in the arid areas of northwest China,where extreme mega-drought events considerably impact vegetation,frozen soil,and other ecological elements.This paper uses three hydroclimate reconstruction datasets to analyze the occurrence,evolution,and possible driving mechanism of megadrought and pluvial events in the Qilian Mountains over the past 500 years.The results showed that the cli-mate in the Qilian Mountains has shown a clear wetting trend since the recent decades,and the wetness trend af-ter 1951 has exceeded the range of natural variability in the historical period.The RAP dataset provided a good representation of the historical dry and wet conditions in the study area.Significant variations were observed in precipitation during the past seven megadrought events in the region,with the highest severity occurring during the drought period of 1786-1796.Furthermore,considerable variations were noted in the duration of the four megapluvial events,with the longest duration being a wet event that lasted for 42 years from 1968 to 2009.Mega-drought and pluvial events were influenced by climate forcing and internal variability of sea surface temperatures(SST).The decadal SST modes in the Pacific and Atlantic Oceans and their phase combinations were key factors regulating the megadrought and pluvial events in the Qilian Mountains.Solar radiation exhibited an in-phase vari-ation with the precipitation in the Qilian Mountains,while volcanic activity primarily affected megadrought events.This study highlights the importance of a long-term perspective for assessing current hydroclimate anoma-lies in the Qilian Mountains and including possible roles of external forcing and sea surface temperature variabili-ty in assessing the future megadrought and pluvial risks in this region.